scheduler now crashes

Author: tombl

arch/wasm/include/asm/thread_info.h

@@ -11,7 +11,7 @@
 struct thread_info {
 	unsigned long flags;
 	int preempt_count;
-	// struct task_struct *from_sched;
+	struct task_struct *from_sched;
 	// unsigned int cpu;
 	unsigned int instance_id;
 	void* jmpbuf;

arch/wasm/kernel/process.c

@@ -12,84 +12,76 @@ void longjmp(void *buf, int val) __attribute__((noreturn));
 static void *get_stack_pointer(void)
 {
 	void *ptr;
-	__asm("global.get __stack_pointer\n"
-	      "local.set %0"
-	      : "=r"(ptr));
+	__asm__ volatile("global.get __stack_pointer\n"
+			 "local.set %0"
+			 : "=r"(ptr));
 	return ptr;
 }
 
 static void __always_inline set_stack_pointer(void *ptr)
 {
-	__asm("local.get %0\n"
-	      "global.set __stack_pointer" ::"r"(ptr));
+	__asm__ volatile("local.get %0\n"
+			 "global.set __stack_pointer" ::"r"(ptr));
 }
 
-struct task_struct *__switch_to(struct task_struct *from,
-				struct task_struct *to)
+static struct task_struct *prev = &init_task;
+
+inline static struct task_struct *__switch_to_inner(struct task_struct *from,
+						    struct task_struct *to)
 {
 	struct pt_regs *from_regs = task_pt_regs(from);
 	struct pt_regs *to_regs = task_pt_regs(to);
 	struct thread_info *from_info = task_thread_info(from);
 	struct thread_info *to_info = task_thread_info(to);
 
-	// the following call crashes clang:
-	// from_info->jmpbuf = kmalloc(40, 0);
-
-	// to_info->from_sched = from;
-	current = to;
-	from_regs->current_stack = get_stack_pointer();
-
-	
 	if (setjmp(from_info->jmpbuf) == 0) {
 		set_stack_pointer(to_regs->current_stack);
-		
-		schedule_tail(from);
-		pr_info("switch %u -> %u\n", from->pid, to->pid);
-		// if (to_info->from_sched)
-		// 	schedule_tail(to_info->from_sched);
-		// to_info->from_sched = NULL;
+
+		if (to_info->from_sched)
+			schedule_tail(to_info->from_sched);
+		to_info->from_sched = NULL;
 
 		if (to_regs->fn) {
 			int (*fn)(void *) = to_regs->fn;
+			int result;
+
 			to_regs->fn = NULL;
+			pr_info("call %p(%p)\n", fn, to_regs->fn_arg);
 
 			// callback returns if the kernel thread execs a process?
-			fn(to_regs->fn_arg);
+			result = fn(to_regs->fn_arg);
+			pr_info("call %p(%p) = %u\n", fn, to_regs->fn_arg,
+				result);
 		} else {
+			pr_info("longjmp %p to %u\n", to_info->jmpbuf, to->pid);
 			longjmp(to_info->jmpbuf, 1);
 		}
+	} else {
+		pr_info("free %p\n", from_info->jmpbuf);
+		kfree(from_info->jmpbuf);
 	}
 
-	kfree(from_info->jmpbuf);
-
-	// pr_info("hi %u %u %u\n", from->pid, to->pid, current->pid);
-	// return current_thread_info()->from_sched;
-	return from;
-
-	// from_regs->current_stack = get_stack_pointer();
-
-	// if (setjmp(from_info->jmpbuf) == 0) {
-	// 	pr_info("context switch %u %p\n"
-	// 		"            -> %u %p\n",
-	// 		from->pid, from_regs->current_stack, to->pid,
-	// 		to_regs->current_stack);
-
-	// 	set_stack_pointer(to_regs->current_stack);
-	// 	pr_info("before jmp %u -> %u\n", current->pid, to->pid);
-	// 	current = to;
+	return prev;
+}
 
-	// 	schedule_tail(from);
+struct task_struct *__switch_to(struct task_struct *from,
+				struct task_struct *to)
+{
+	struct pt_regs *from_regs = task_pt_regs(from);
+	struct pt_regs *to_regs = task_pt_regs(to);
+	struct thread_info *from_info = task_thread_info(from);
+	struct thread_info *to_info = task_thread_info(to);
 
-	// 	pr_info("regs: %p %p\n", to_regs, to_regs->fn);
+	from_regs->current_stack = get_stack_pointer();
+	from_info->jmpbuf = kmalloc(16, 0);
 
-	// 	longjmp(to_info->jmpbuf, 1);
-	// }
+	pr_info("alloc %p for %u\n", from_info->jmpbuf, from->pid);
 
-	// set_stack_pointer(from_regs->current_stack);
-	// pr_info("resuming from jmp %u -> %u\n", current->pid, from->pid);
-	// current = from;
+	current = to;
+	to_info->from_sched = prev;
+	prev = from;
 
-	// return from;
+	return __switch_to_inner(from, to);
 }
 
 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
@@ -103,8 +95,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 	if (!args->fn)
 		panic("can't copy userspace thread"); // yet
 
-	// pr_info("copying thread %i %p\n", p->pid, childregs);
-
 	childregs->fn = args->fn;
 	childregs->fn_arg = args->fn_arg;
 

kernel/sched/core.c

@@ -6511,7 +6511,6 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 			 *
 			 * After this, schedule() must not care about p->state any more.
 			 */
-			pr_info("deactivating %s %lx %u %u\n", prev->comm, prev_state, prev->pid, prev->sched_class->rank);
 			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
 
 			if (prev->in_iowait) {

kernel/sched/fair.c

@@ -6173,7 +6173,6 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	bool was_sched_idle = sched_idle_rq(rq);
 
 	early_printk("dequeue %u %s\n", p->pid, p->comm);
-	wasm_breakpoint();
 
 	util_est_dequeue(&rq->cfs, p);
 

kernel/sched/swait.c

@@ -26,7 +26,6 @@ void swake_up_locked(struct swait_queue_head *q)
 		return;
 
 	curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
-	pr_info("curr: %p %p\n", curr, &curr->task);
 	wake_up_process(curr->task);
 	list_del_init(&curr->task_list);
 }